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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Dec 2025 03:43:48.3486 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a1d3d5e6-429c-4136-b467-08de3930a8a6 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN2PEPF000055DF.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR12MB4132 Hi Ian, >>> Next is CPU scheduling statistics. These are simple diffs of >>> /proc/schedstat CPU lines along with description. The report also >>> prints % relative to base stat. > > I wonder if this is similar to user_time and system_time: > ``` > $ perf list > ... > tool: > ... > system_time > [System/kernel time in nanoseconds. Unit: tool] > ... > user_time > [User (non-kernel) time in nanoseconds. Unit: tool] > ... > ``` > These events are implemented by reading /proc/stat and /proc/pid/stat: > https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/util/tool_pmu.c?h=perf-tools-next#n267 > > As they are events then they can appear in perf stat output and also > within metrics. Create synthesized events for each field of /proc/schedstat? Your idea is interesting and, I suppose, will work best when we care about individual counters. However, for the "perf sched stats" tool, I see atleast two challenges: 1. One of the design goal of "perf sched stats" was to keep the overhead low. Currently, it reads /proc/schedstat once at the beginning and once at the end. Switching to per-counter events would require opening, reading and closing a large number of events which would incur significant overhead. 2. Taking a snapshot in one go allows us to correlate counts easily. Using synthetic events would force us to read each counter individually, making cross-counter correlation impossible. Thanks, Ravi